In many applications in the fluid field, in particular for cooling vehicle heat engines, thermostatic valves are used to regulate the flow of a fluid, i.e., to distribute this incoming fluid in different flow pathways, based on the temperature of that fluid. These valves are said to be thermostatic inasmuch as the movement of their inner obturator relative to the housing of the valve is controlled by a thermostatic element, i.e., an element that comprises a body, containing a thermodilatable material, and a piston, submerged in this thermodilatable material, the body and the piston being movable relative to one another in translation along the longitudinal axis of the piston, while either the body or the piston is, during use, fixedly connected to the housing of the valve.
To seal the contact between the obturator moved by the thermostatic element and a fixed seat of the housing, it is known to incorporate a gasket into the obturator. This gasket, typically made from a flexible material such as rubber or elastomer, is supported by a rigid frame of the obturator, this frame being, during use, fixedly connected to the moving part of the thermostatic element so that it can be driven by the thermostatic element. In practice, the gasket is kept in place on this frame by overmolding, crimping or shape matching. These solutions, which are old and very widespread, are effective, but relatively expensive to implement.
More recently, U.S. Pat. No. 8,028,926 proposed embedding a gasket between two plates of the obturator, which are fixedly secured to one another, in particular by clipping through the gasket, at least one of these plates being made from plastic. These two plates are provided to be coaxial and inwardly receive the moving part of the thermostatic element, to which they are fixedly connected during use. This solution has limited mechanical strength, regarding both high fluid pressures and over the long term, with leakage risks at the obturator.